The present invention relates to a light fixture. More specifically, the present invention relates to a light fixture having a reflector configuration for providing a desired beam pattern.
Lighting devices, with incandescent or arc discharge lamps, have been provided with reflectors for many years. The reflectors typically reside behind the lamp and reflect or redirect light or other radiation produced by the lamp in a desired direction. It is often desired to have an electromagnetic radiation source (a lamp) that radiates the electromagnetic radiation in the visible spectrum (light) on a particular area. Such applications include sports stadiums, sports arenas, and other commercial and industrial applications.
In many applications, the electromagnetic radiation is derived from a plasma arc formed within an electromagnetic transmissive envelope or arc tube. One form of such an arc discharge lamp is a metal halide lamp. In such lamps, the arc is ignited between two electrodes placed at opposite ends of the electromagnetic transmissive envelope. These electrodes define an envelope axis and are connected to a power supply which supplies the proper voltage and current for starting and operating the lamp.
Prior arc discharge lamps also included a reflecting surface, such as a single parabolic sheet reflecting surface bounded by opposing planar surfaces. The reflecting surface had a predetermined focal axis. Such a parabolic sheet reflector surface results in a beam pattern reflected on the desired area which is typically longer along a horizontal axis than along a vertical axis. The beam pattern provides lower intensity light at the outer ends of the horizontal axis.
Arc discharge lamps have also been provided with reflectors of other shapes, such as elliptic or parabolic shapes. However, such reflectors commonly result in a circular beam pattern. This can result in certain inefficiencies where desired lighting effects are sought.
In certain lighting venues, such as arenas or stadiums, it is desirable to have the entire lighted surface uniformly illuminated. In using prior parabolic sheet-type reflectors, or elliptical or paraboloid-type reflectors, the beam patterns needed to be significantly overlapped in order to illuminate the entire lighted surface. For example, with a parabolic sheet-type reflector, the illumination at the horizontal extremes of the beam pattern were required to be overlapped. This resulted in unwanted fringing effects in overlapped regions of the beam patterns of two or more lamps. In addition, with elliptic or paraboloid-type reflectors, the resultant round beam pattern made it very difficult to uniformly illuminate a surface. Round beam patterns were difficult to fit together and therefore needed to overlap one another resulting in bright and dim spots on the illuminated surface.
Another problem encountered in attempting to provide lighting for arenas is that the lighting systems are typically mounted to catwalks which are hung high above the arena floor. The catwalks are typically metal catwalks with pipe railings. Typical catwalks have either two or three railings, and the spacing between the railings differs widely from arena to arena and catwalk to catwalk. Therefore, mounting devices for mounting light fixtures to the railings on the catwalks have, to date, been specifically custom designed for each arena, based on rail spacing of the catwalks from which the lighting fixtures are to be hung. Such custom design is expensive and inefficient.